In recent years, progress is being made in research and development of organic EL elements, which are light-emitting elements that use electroluminescence of a solid fluorescent material. Because organic EL elements are self-luminous elements, an organic EL display panel having such organic EL elements arranged in rows and columns on a TFT substrate offers advantages including high visibility and excellent shock resistance. An organic EL element is fabricated by laminating layers including an organic light-emitting layer between a pixel electrode (anode) and a common electrode (cathode), the organic light-emitting layer emitting light as a result of recombination of carriers (holes and electrons).
Examples of methods for manufacturing such organic light-emitting layers include a vapor deposition method and a printing method. Especially, when an inkjet method, which is a type of printing methods, is employed to form organic light-emitting layers, it is necessary to provide barriers (banks) formed, for example, from an insulating material between adjacent pixels in order to prevent ink drops from mixing into ink drops of a different color dripped into adjacent pixels. One method for forming banks is a line-bank method according to which a plurality of banks are formed in parallel lines so that organic light-emitting layers are partitioned into stripes (see Patent Literature 1, for example). Another method is a pixel-bank method according to which a grid-like (lattice-like) bank is formed to surround individual pixels.
FIG. 11 is a schematic sectional view showing the structure of an organic EL display panel 900 having banks formed by a typical line-bank method. Disposed on the upper surface of a substrate 91 are SD electrodes (source-drain electrodes) 92 of thin-film transistors that are for driving the organic EL elements. In addition, an interlayer insulation film 93 is disposed to coat the SD electrodes 92. Pixel electrodes 94 are disposed over (i.e., on or above) the interlayer insulation film 93 and connected to the SD electrodes 92 via contact holes 95 formed in the interlayer insulation film 93. Pixel-defining layers 96 are disposed over the pixel electrodes 94 in a manner to coat the edges of different pixel electrodes 94, the edges facing in the lateral direction in the figure. Over the pixel electrodes 94 and the pixel-defining layers 96, organic light-emitting layers 97 and a common electrode 98 are layered in order. In the organic EL display panel 900 having the above structure, portions of the organic light-emitting layers 97 constitute light-emitting portions are those located above the regions A9. Each region A9 is a region of the pixel electrode 94 excluding where the pixel-defining layer 96 is disposed.